Spring mvc的jdbc查询：queryForInt(java.lang.String sql, java.lang.Object... args)
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补充：queryForInt(java.lang.String sql,
java.lang.Object... args)
queryForInt(java.lang.String sql,
java.lang.Object[] args, int[] argTypes)
这是spring的jdbc的两种查询方式，第二种方式中的int[]参数是什么意思？
另外如何将第一种方式重载成 queryForInt(java.lang.String sql, java.lang.Object[] args) 类型
数据库的类型，我如何用 int[] 来保存？
追答这是因为这里的argTypes就是int类型
比如第二种方法，
this.queryForInt("", new Object[]1,"name",new int[]java.sql.Types.INTEGER,java.sql.Types.VARCHAR);
Spring JDBC实现查询
1 db.properties
1 jdbc.user=root 2 jdbc.password=920614 3 jdbc.driverClass=com.mysql.jdbc.Driver 4 jdbc.jdbcUrl=jdbc:mysql:///spring?useUnicode=true&characterEncoding=utf-8 5 6 jdbc.initPoolSize=5 7 jdbc.maxPoolSize=10
2 applicationContext.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xmlns:aop="http://www.springframework.org/schema/aop" 5 xmlns:c="http://www.springframework.org/schema/c" 6 xmlns:context="http://www.springframework.org/schema/context" 7 xmlns:jdbc="http://www.springframework.org/schema/jdbc" 8 xmlns:p="http://www.springframework.org/schema/p" 9 xmlns:tx="http://www.springframework.org/schema/tx" 10 xmlns:util="http://www.springframework.org/schema/util" 11 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 12 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd 13 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd 14 http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.0.xsd 15 http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd 16 http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd"> 17 18 19 <context:component-scan base-package="com.spring.jdbc"></context:component-scan> 20 <!-- 导入资源文件 --> 21 <context:property-placeholder location="classpath:db.properties"/> 22 <!-- 配置C3P0数据源 --> 23 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> 24 <property name="user" value="${jdbc.user}"></property> 25 <property name="password" value="${jdbc.password}"></property> 26 <property name="driverClass" value="${jdbc.driverClass}"></property> 27 <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property> 28 29 <property name="initialPoolSize" value="${jdbc.initPoolSize}"></property> 30 <property name="maxPoolSize" value="${jdbc.maxPoolSize}"></property> 31 32 </bean> 33 34 <!-- 配置Spring的JdbcTemplate --> 35 <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate"> 36 <property name="dataSource" ref="dataSource"></property> 37 </bean> 38 39 <!-- 配置 NamedParameterJdbcTemplate, 40 该对象可以使用具名参数, 其没有无参数的构造器, 所以必须为其构造器指定参数 --> 41 <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate"> 42 <constructor-arg ref="dataSource"></constructor-arg> 43 </bean> 44 45 <!-- 配置事务管理器 --> 46 <bean id="transactionManager" 47 class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> 48 <property name="dataSource" ref="dataSource"></property> 49 </bean> 50 51 <!-- 启用事务注解 --> 52 <tx:annotation-driven transaction-manager="transactionManager"/> 53 54 </beans>
3 com.spring.jdbc
实体类
1 package com.spring.jdbc; 2 3 public class Employee { 4 private int id; 5 private String lastName; 6 private String email; 7 8 private int deptId; 9 10 11 public int getDeptId() { 12 return deptId; 13 } 14 public void setDeptId(int deptId) { 15 this.deptId = deptId; 16 } 17 public int getId() { 18 return id; 19 } 20 public void setId(int id) { 21 this.id = id; 22 } 23 public String getLastName() { 24 return lastName; 25 } 26 public void setLastName(String lastName) { 27 this.lastName = lastName; 28 } 29 public String getEmail() { 30 return email; 31 } 32 public void setEmail(String email) { 33 this.email = email; 34 } 35 @Override 36 public String toString() { 37 return "Employee [id=" + id + ", lastName=" + lastName + ", email=" 38 + email + ", deptId=" + deptId + "]"; 39 } 40 41 42 }
EmployeeDao.java
1 package com.spring.jdbc; 2 3 import org.springframework.beans.factory.annotation.Autowired; 4 import org.springframework.jdbc.core.BeanPropertyRowMapper; 5 import org.springframework.jdbc.core.JdbcTemplate; 6 import org.springframework.jdbc.core.RowMapper; 7 import org.springframework.stereotype.Repository; 8 9 @Repository 10 public class EmployeeDao { 11 12 @Autowired 13 private JdbcTemplate jdbcTemplate; 14 15 public Employee get(int id){ 16 String sql="SELECT id,last_name lastName,email,dept_id FROM employees WHERE id=?"; 17 RowMapper<Employee> rowMapper=new BeanPropertyRowMapper<>(Employee.class); 18 Employee employee=jdbcTemplate.queryForObject(sql, rowMapper,id); 19 20 return employee; 21 22 23 } 24 }
1 package com.spring.jdbc; 2 3 import java.sql.SQLException; 4 import java.util.ArrayList; 5 import java.util.HashMap; 6 import java.util.List; 7 import java.util.Map; 8 9 import javax.sql.DataSource; 10 11 import org.junit.Test; 12 import org.springframework.context.ApplicationContext; 13 import org.springframework.context.support.ClassPathXmlApplicationContext; 14 import org.springframework.jdbc.core.BeanPropertyRowMapper; 15 import org.springframework.jdbc.core.JdbcTemplate; 16 import org.springframework.jdbc.core.RowMapper; 17 import org.springframework.jdbc.core.namedparam.BeanPropertySqlParameterSource; 18 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate; 19 import org.springframework.jdbc.core.namedparam.SqlParameterSource; 20 21 public class JdbcTest { 22 23 private ApplicationContext ctx=null; 24 private JdbcTemplate jdbcTemplate=null; 25 private EmployeeDao employeeDao ; 26 private DepartmentDao departmentDao ; 27 private NamedParameterJdbcTemplate namedParameterJdbcTemplate=null; 28 { 29 ctx=new ClassPathXmlApplicationContext("beans-dataSource.xml"); 30 jdbcTemplate =(JdbcTemplate) ctx.getBean("jdbcTemplate"); 31 employeeDao = ctx.getBean(EmployeeDao.class); 32 departmentDao = ctx.getBean(DepartmentDao.class); 33 namedParameterJdbcTemplate=(NamedParameterJdbcTemplate) ctx.getBean("namedParameterJdbcTemplate"); 34 35 } 36 37 38 39 /** 40 * 使用具名参数时, 可以使用 update(String sql, SqlParameterSource paramSource) 方法进行更新操作 41 * 1. SQL 语句中的参数名和类的属性一致! 42 * 2. 使用 SqlParameterSource 的 BeanPropertySqlParameterSource 实现类作为参数. 43 */ 44 @Test 45 public void testNamedParameterJdbcTemplate2(){ 46 String sql="INSERT INTO employees(last_name,email,dept_id) VALUES(:lastName,:email,:deptId)"; 47 Employee employee=new Employee(); 48 employee.setLastName("LKQ"); 49 employee.setEmail("[email protected]"); 50 employee.setDeptId(2); 51 52 SqlParameterSource sqlParameterSource =new BeanPropertySqlParameterSource(employee); 53 namedParameterJdbcTemplate.update(sql, sqlParameterSource); 54 55 } 56 /** 57 * 可以为参数起名字. 58 * 1. 好处: 若有多个参数, 则不用再去对应位置, 直接对应参数名, 便于维护 59 * 2. 缺点: 较为麻烦. 60 */ 61 @Test 62 public void testNamedParameterJdbcTemplate(){ 63 String sql="INSERT INTO employees(last_name,email,dept_id) VALUES(:name,:email,:deptid)"; 64 Map<String,Object> paramMap=new HashMap<>(); 65 paramMap.put("name", "XJP"); 66 paramMap.put("email", "[email protected]"); 67 paramMap.put("deptid",001); 68 69 namedParameterJdbcTemplate.update(sql, paramMap); 70 } 71 72 73 74 @Test 75 public void testDepartmentDao(){ 76 System.out.println(departmentDao.get(2)); 77 } 78 @Test 79 public void testEmployeeDao(){ 80 System.out.println(employeeDao.get(2)); 81 } 82 83 /** 84 * 从数据库中获取记录对象集合 85 */ 86 @Test 87 public void testQueryForList(){ 88 String sql="SELECT id,last_name lastName,email,dept_id FROM employees WHERE id>?"; 89 RowMapper<Employee> rowMapper=new BeanPropertyRowMapper<>(Employee.class); 90 List<Employee> employees=jdbcTemplate.query(sql, rowMapper,8); 91 92 System.out.println(employees); 93 } 94 95 96 /** 97 * 从数据库中获取单个列的值，统计查询 98 */ 99 @Test 100 public void testQueryForObject2(){ 101 String sql="SELECT count(id) FROM employees"; 102 long count=jdbcTemplate.queryForObject(sql, Long.class); 103 System.out.println(count); 104 } 105 106 107 /** 108 * 从数据库中获取一条记录, 实际得到对应的一个对象 109 */ 110 @Test 111 public void testQueryForObject(){ 112 String sql="SELECT id,last_name lastName,email,dept_id FROM employees WHERE id=?"; 113 RowMapper<Employee> rowMapper=new BeanPropertyRowMapper<>(Employee.class); 114 Employee employee=jdbcTemplate.queryForObject(sql, rowMapper,2); 115 System.out.println(employee); 116 } 117 118 /** 119 * 执行批量更新: 批量的 INSERT, UPDATE, DELETE 120 * 最后一个参数是 Object[] 的 List 类型: 因为修改一条记录需要一个 Object 的数组, 那么多条不就需要多个 Object 的数组吗 121 */ 122 @Test 123 public void testBatchUpdate(){ 124 String sql="INSERT INTO employees(last_name,email,dept_id) VALUES(?,?,?)"; 125 126 List<Object[]> batchArgs=new ArrayList<>(); 127 batchArgs.add(new Object[]{"AA", "[email protected]", 1}); 128 batchArgs.add(new Object[]{"BB", "[email protected]", 2}); 129 batchArgs.add(new Object[]{"CC", "[email protected]", 3}); 130 batchArgs.add(new Object[]{"DD", "[email protected]", 3}); 131 batchArgs.add(new Object[]{"EE", "[email protected]", 2}); 132 133 jdbcTemplate.batchUpdate(sql, batchArgs); 134 } 135 /** 136 * 执行 INSERT, UPDATE, DELETE 137 */ 138 @Test 139 public void testUpdate(){ 140 String sql="UPDATE employees SET last_name = ? WHERE id=?"; 141 jdbcTemplate.update(sql,"王根深",2); 142 } 143 @Test 144 public void testDataSource() throws SQLException{ 145 DataSource dataSource =(DataSource) ctx.getBean("dataSource"); 146 System.out.println(dataSource.getConnection()); 147 } 148 }
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